First let us deal with the overall attitude of the photo post and how to convey that right attitude. It is really all up to you and how you want to come across to a total stranger. Remember that in the world of online dating the photo post is probably considered the first impression to a lot of people and first impressions cannot be changed. So if you want to convey an attitude of carefree and fun to be with then your photo post needs to be of you having fun preferably in a group. If you are trying to attract fun people then you want to let them know that you have a group of friends and that you are not a lonely person cruising the internet. Make sure that you can clearly be seen in any picture you decide to use because if you have a picture of you frolicking with friends somewhere and you are hiding behind a tree then that is not going to work. Make sure you are the very center of the picture and you can clearly be seen completely. You can accomplish this by cropping an existing picture you have, as long as you can clearly be seen in it, or telling your friends what you are doing and have a get together to take pictures. Remember that you many want to keep the drugs and alcohol out of the picture as that can probably turn most decent people off and wind up attracting people you don’t want.
The other side of that is the very serious picture that is usually either taken in a studio with a professional or by a friend of yours using a digital camera. Do not use a three year old picture that you have always used as that will make things very awkward when you meet your prospective date face to face. No matter how much you insist the fact is that you do not look the same now as you did three years ago and a current picture is the best one to put up. Make sure you give a pleasant smile and also make sure you have a pleasant look on your face. The point of the serious picture is to convey a serious image. If you want to get goofy then see the previous paragraph. Dress conservative but contemporary as dressing suggestively wil definitely attract the wrong element. Make sure the picture is clear and looks pleasant. If your first try looks like a huge picture of a flash bulb then try again. Depending on how serious you are about this you may want to take the professional approach I suggested earlier.
How you look is all up to you. A photo post on your online dating profile is your first impression so be sure to make it what you want it to be and be ready to accept the consequences if you put up a picture that gives the wrong impression. It is true when they say that a picture can say a thousand words.